On screen, they are two inseparable sisters

 "The relationship between Shannen Doherty (Prue) and Alyssa Milano (Phoebe) is a story of two extremes.

On screen, they are two inseparable sisters. But in real life, the differences in their personalities and the pressure of fame created great tension on set.
This conflict was the main reason why Shannen left Charmed after season 3, an event that caused great regret.
Many years later, both looked back with more maturity, expressing regret and understanding for what happened.
Despite the storms, it is undeniable that their dramatic interactions created the soul of the first seasons and contributed to the legend of Charmed."